TWI846966B - Method of forming a photoresist underlayer and structure including same - Google Patents

Abstract

Methods of forming structures including a photoresist underlayer and structures including the photoresist underlayer are disclosed. Exemplary methods include forming the photoresist underlayer that includes metal. Techniques for treating a surface of the photoresist underlayer and/or depositing an additional layer overlying the photoresist underlayer are also disclosed.

Description

Method for forming photoresist bottom layer and structure including photoresist bottom layer

The present disclosure generally relates to structures and methods of forming the structures. More specifically, the present disclosure relates to structures including or formed using photoresist layers and methods of forming such structures.

During the fabrication of electronic devices, fine patterns of features can be formed on a substrate surface by patterning the substrate surface and etching material from the substrate surface using, for example, a vapor phase etching process. As the density of devices on a substrate increases, it becomes increasingly desirable to form features having smaller dimensions.

Photoresists are often used to pattern substrate surfaces prior to etching. A pattern is formed in the photoresist by applying a layer of photoresist to the substrate surface, masking the photoresist surface, exposing unmasked portions of the photoresist to radiation (such as ultraviolet light), and removing a portion of the photoresist (e.g., the unmasked or masked portion) while leaving a portion of the photoresist on the substrate surface.

Recently, techniques using extreme ultraviolet (EUV) wavelengths have been developed to develop patterns with relatively small features (e.g., 10 nm or less). To form features on a substrate using EUV, a photoresist base layer of spin-on-glass (SOG) is typically deposited onto the substrate surface, followed by a EUV photoresist layer overlying the SOG base layer. The base layer generally has a thickness of about 10 nm or more.

As the size of device features decreases, the bottom layer can be made thinner as desired, for example to allow the formation of etched features with a desired pitch resolution and/or aspect ratio. Unfortunately, it can be difficult to deposit SOG at a thickness less than 10 nm. Further, the thickness non-uniformity of the deposited SOG can be undesirably high within and between substrates, particularly as the target thickness of the SOC layer is reduced.

Another challenge encountered when trying to increase the resolution of lithography patterning techniques, especially those using EUV resists, is regarding the EUV resist profile after the resist has been exposed and developed. After exposure and development, the resist profile can appear tapered. If the resist line is less wide at the bottom of the structure than at the top, the line may collapse. If it goes the other way (the line is wider at the bottom than at the top), the line will be very stable on the substrate surface, but the pattern will be difficult to transfer and it will result in higher line edge roughness/line width roughness values.

Another challenge encountered when attempting to increase the resolution of lithographic patterning techniques, particularly those involving EUV photoresists, is related to induced porosity in underlying layers (e.g., carbon hardmasks) exposed to deposition and/or surface treatments involving the use of plasma.

For at least these reasons, what are desired are improved structures including photoresist underlayers, such as underlayers suitable for use with EUV, and methods of forming such structures. Specifically desired are underlayers that have good adhesion to EUV photoresists, have a thickness of less than about 5 nm, and are resistant to etching chemistries that may be used to etch underlying layers.

The following prior art document is recorded: Dufond, Maxime E. et al. "Quantifying the Extent of Ligand Incorporation and the Effect on Properties of TiO2 Thin Films Grown by Atomic Layer Deposition Using an Alkoxide or an Alkylamide." Chemistry of Materials 32.4 (2020): pp. 1393-1407.

Any discussion of problems and solutions presented in this section is included in the present disclosure for the purpose of providing a background for the present disclosure only, and should not be regarded as an admission that any or all of the contents of the discussion were known at the time of making the present invention.

Various embodiments of the present disclosure relate to structures including improved photoresist base layers (sometimes referred to as adhesion layers) and methods of forming layers and structures. Although the manner in which various embodiments of the present disclosure address shortcomings of previous methods and structures is discussed in more detail below, in general, various embodiments of the present disclosure provide structures that may include relatively thin, uniform photoresist base layers having desired properties (such as desired etch selectivity, pattern quality, and/or stability). Further, exemplary photoresist base layers may be formed using a cyclic process (such as atomic layer deposition) that allows precise control of the thickness of the photoresist base layer on a substrate surface and from substrate to substrate. Furthermore, as set forth in more detail below, precursors, deposition conditions, post-deposition processing parameters, and the like may be adjusted or selected to form a photoresist base layer having a desired surface energy to promote a desired adhesion between the photoresist base layer and an overlying photoresist.

According to an exemplary embodiment of the present disclosure, a method of forming a structure includes providing a substrate, forming a photoresist base layer overlying the substrate surface, and forming a layer of photoresist overlying the photoresist base layer. The photoresist base layer may include a metal (such as a transition metal). For example, the photoresist base layer may be or include one or more of a metal oxide, a metal nitride, and a metal oxynitride. The photoresist base layer may be formed using one or more of a plasma enhanced cyclic (e.g., atomic layer) deposition process and a thermal cycle deposition process. For example, the cyclic deposition process may include a step of providing one or more metal precursors to a reaction chamber; a step of providing one or more of an oxidizer and a nitrider to the reaction chamber; and in some cases, a step of providing one or more carbon precursors to the reaction chamber. The photoresist base layer may have a thickness of less than 10 nm or less than 5 nm. The photoresist layer may be or may include a positive or negative extreme ultraviolet (EUV) lithography photoresist.

According to exemplary aspects of the present disclosure, the photoresist underlayer includes carbon. For example, the photoresist underlayer may include greater than 0.18 g/cm ³ , or greater than 5 at%, or about 5 at% to about 30 at% carbon. In some cases, a carbon concentration in the photoresist underlayer may vary with the height of the photoresist underlayer (e.g., a carbon concentration near a top surface of the photoresist underlayer (e.g., in the top 1 to 2 nm) may be greater than the carbon concentration in the lower portion or bulk of the photoresist underlayer). In these cases, a carbon concentration in the top surface of the photoresist underlayer may be greater than 10 at%, or about 10 at% to about 50 at% carbon.

According to exemplary aspects of embodiments of the present disclosure, the photoresist base layer can be selected and/or formulated to have desired properties (e.g., desired surface energy properties), for example, to promote desired adhesion between the photoresist base layer and an overlying photoresist layer. For example, as set forth in more detail below, various precursors, process conditions, treatments, and/or coatings can be employed to obtain desired photoresist base layer surface energy properties. Exemplary values for a polar portion of the surface energy of the photoresist base layer are between about 5 mN/m and about 25 mN/m or between about 20 mN/m and about 40 mN/m. Exemplary values of a distributed portion of the surface energy of the photoresist bottom layer are between 10 mN/m and about 30 mN/m, or between 5 mN/m and about 25 mN/m, or between 20 mN/m and about 40 mN/m.

According to some aspects of the present disclosure, the methods may include a step of forming a carbon-containing layer overlying the photoresist base layer. The carbon-containing layer may be used to obtain a desired surface energy or may be treated to obtain a desired surface energy. Exemplary carbon-containing layers may include silicon, oxygen, and carbon. Additionally or alternatively, the carbon-containing layer may include amorphous carbon.

Exemplary methods may additionally or alternatively include a step of treating a surface, such as a surface of the photoresist base layer. Exemplary treatments for modifying a surface energy of a photoresist base layer include exposing a surface of the photoresist base layer to one or more carbon-containing agents. Exemplary carbon-containing agents may include a chemical formula including C, O, and optionally N. For specific examples, the carbon-containing agent may be selected from the group consisting of one or more of the following: anhydrides (e.g., acetic anhydride), toluene, diethylene glycol, triethylene glycol, acetaldehyde, silanes, and siloxanes. Using a carbon-containing agent to form CH3-terminated molecules on a surface may reduce the polar portion of the surface energy to near zero, but may not appreciably change the dispersed portion of the surface energy. Additionally or alternatively, a surface of the photoresist base layer or a carbon-containing layer thereon may be treated with a fluorine-containing precursor (e.g., perfluorodecyltrimethoxysilane) to, for example, reduce a polar portion of the surface energy of the photoresist base layer and reduce the dispersed portion. The surface may also be treated with a surface functionalizing agent (e.g., a halogenating agent, such as silanes and siloxanes). Further examples of suitable surface treatments/carbon-containing layers include self-assembled layers (e.g., monolayers). The self-assembled layer may be formed using precursors that include one or more of silicon and carbon (e.g., silanes, siloxanes, fluorinated silanes, and/or fluorinated siloxanes).

According to additional exemplary embodiments of the present disclosure, a structure is provided that includes a photoresist bottom layer. The photoresist bottom layer can be formed using methods as described herein. The photoresist bottom layer can include, for example, a layer that includes a metal (such as one or more of a metal oxide, a metal nitride, and a metal oxynitride). As described herein, exemplary structures can include one or more carbon-containing layers (such as an amorphous carbon layer and/or a SiOC layer). A photoresist bottom layer can be treated or functionalized using the techniques described herein. The photoresist bottom layer (alone or in combination with a carbon layer and/or any of the treatments) can have surface energy properties as described herein. Exemplary structures can also include a layer of photoresist (such as a negative or positive EUV photoresist).

A method of forming a structure including a photoresist layer is further described, the method comprising the following steps: providing a substrate; forming a photoresist layer overlying a surface of the substrate; wherein the photoresist layer comprises a metal.

In some embodiments, the photoresist bottom layer includes one or more of a metal oxide, a metal nitride, and a metal oxynitride.

In some embodiments, the metal comprises one or more transition metals.

In some embodiments, a value of a polar portion of the surface energy of the photoresist bottom layer is between about 5 mN/m and about 25 mN/m or between about 20 mN/m and about 40 mN/m.

In some embodiments, a value of a distributed portion of the surface energy of the photoresist bottom layer is between about 10 mN/m and about 30 mN/m, or between about 5 mN/m and about 25 mN/m, or between about 20 mN/m and about 40 mN/m.

In some embodiments, the photoresist underlayer further comprises greater than 0.18 g/cm3 or 5 atomic percent carbon.

In some embodiments, the photoresist bottom layer is formed using a cyclic deposition process.

In some embodiments, the photoresist bottom layer is formed using an atomic layer deposition process.

In some embodiments, the photoresist bottom layer is formed using a cyclic chemical vapor deposition process.

In some embodiments, a carbon precursor is provided to the reaction chamber during the step of forming a photoresist base layer.

In some embodiments, the carbon precursor has a chemical formula comprising C and O.

In some embodiments, the carbon precursor comprises one or more of an organic compound, a carboxylic anhydride, toluene, diethylene glycol, triethylene glycol, acetaldehyde, and an organic silicon compound (such as silane and siloxane).

In some embodiments, the organic silicon compound is selected from the group consisting of N,N-dimethylaminotrimethylsilane, octadecyltrimethoxysilane, trimethoxyphenylsilane, (3,3,3-trifluoropropyl)trichlorosilane, and hexamethyldisilazane.

In some embodiments, the photoresist underlayer comprises a metal, oxygen, and carbon, and a metal-containing precursor is provided to the reaction chamber during the step of forming a photoresist underlayer, wherein the metal-containing precursor is an alkoxide or alkamide metal precursor.

In some embodiments, the metal-containing precursor has a general formula M[R( _{CxHy ) n} ] ₄ , wherein M is selected from Ti, Ta, Hf, Zn, and Zr; and R is selected from OCH and N, wherein x is 1-2, wherein y is 3-6, and wherein n is 2-3.

In some embodiments, M is Ti.

In some embodiments, the metal-containing precursor is titanium(IV) isopropoxide.

In some embodiments, the photoresist layer comprises Hf and is deposited using a precursor selected from the group consisting of tetrakis(ethylmethylamido)arium, dimethylbis(cyclopentadienyl)arium, and tertiary arium(IV)butoxide.

In some embodiments, the photoresist underlayer comprises Ta, and the photoresist underlayer is deposited using a precursor selected from penta(dimethylamino)tantalum, ethoxytantalum(V), tris(diethylamino)(tertiary-butylimino)tantalum, tertiary-butylimino tris(ethylmethylamino)tantalum, (dimethylamino)ethoxytetraethoxytantalum, and tertiary-butylimino tris(diethylamido)tantalum.

In some embodiments, the bottom photoresist layer is formed using a thermal ALD or a thermal CVD process using a reactant selected from H ₂ O, O ₃ , and H ₂ O ₂ .

In some embodiments, the reactants include H ₂ O and O ₃ .

In some embodiments, the photoresist bottom layer is formed using a plasma ALD or a plasma enhanced pulsed CVD method, which employs a plasma selected from the list consisting of _H2 , _H2 /He, _H2 /Ar, Ar, and _O2 plasma.

In some embodiments, the method further comprises a surface treatment step.

In some embodiments, the surface treatment step includes exposing the photoresist base layer to one or more carbon-containing compounds.

In some embodiments, the one or more carbon-containing compounds are selected from the group consisting of monocarboxylic anhydride, toluene, diethylene glycol, triethylene glycol, acetaldehyde, and organic silicon compounds (such as silane and siloxane).

In some embodiments, a thickness of the photoresist bottom layer is less than 5 nm.

In some embodiments, the method further comprises a step of forming a carbon-containing layer overlying the photoresist base layer.

In some embodiments, the carbon-containing layer comprises silicon, oxygen, and carbon.

In some embodiments, the carbon-containing layer comprises amorphous carbon.

In some embodiments, the method further comprises a step of forming a self-assembly layer overlying the photoresist base layer.

In some embodiments, the self-assembled layer is formed of a material comprising one or more of silicon and carbon.

In some embodiments, the material comprises one or more Si-C bonds.

In some embodiments, the material is selected from the group consisting of silanes and siloxanes.

In some embodiments, the material is selected from the group consisting of fluorinated silanes and fluorinated siloxanes.

In some embodiments, the material is selected from the group consisting of dimethylaminotrimethylsilane (DMA-TMS), hexamethyldisilazane (HMDS), (3-bromopropyl)trimethoxysilane, (3-iodopropyl)trimethoxysilane, 3-(trimethoxysilyl)propyl acrylate, trimethoxyphenylsilane, trimethoxy(3,3,3-trifluoropropyl)silane, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, tichloro(phenyl)silane, and trimethoxy(1H,1H,2H,2H-heptadecafluorodecyl)silane (FTMS).

In some embodiments, the base layer is formed at a temperature of at least 70°C to at most 300°C.

In some embodiments, the base layer is formed at a temperature of at least 70°C to at most 200°C.

In some embodiments, the base layer is formed at a temperature of at least 200°C to at most 300°C.

In some embodiments, forming the bottom layer includes forming a lower bottom layer portion and an upper bottom layer portion.

In some embodiments, the lower substrate portion is formed using a metal halide precursor.

In some embodiments, the lower bottom _layer portion is formed using a metal-containing precursor having a general formula M[R( _CxHy ) _n ] ₄ , wherein M is selected from Ti, Ta, Hf, Zn, and Zr, wherein R is selected from OCH and N, wherein x is 1-2, wherein y is 3-6, and wherein n is 2-3.

In some embodiments, the upper bottom _layer portion is formed using a metal-containing precursor having a general formula M[R( _CxHy ) _n ] ₄ , wherein M is selected from Ti, Ta, Hf, Zn, and Zr, wherein R is selected from OCH and N, wherein x is 1-2, wherein y is 3-6, and wherein n is 2-3.

In some embodiments, the upper bottom layer portion is formed using plasma enhanced ALD or plasma enhanced chemical vapor deposition, wherein a noble gas is used as a plasma gas.

In some embodiments, the noble gas comprises Ar.

In some embodiments, the upper bottom layer portion comprises silicon, oxide, and carbon, the upper bottom layer portion has a thickness from at least 0.1 nm to at most 2.0 nm, and the upper bottom layer portion is formed using an organic silicon precursor and an oxygen-containing reactant selected from _O2 , _H2O , _O3 , and _{H2O2 .}

In some embodiments, the method includes exposing the base layer to a surface treatment step, the surface treatment comprising exposing the base layer to an organic silicon compound selected from the list consisting of bis(tripropylsilyl)amine, bis(triethylsilyl)amine, bis(trimethylsilyl)amine, (dimethylamino)trimethylsilane, (diethylamino)trimethylsilane, (diethylamino)triethylsilane, and (dimethylamino)triethylsilane.

In some embodiments, the method further comprises a step of exposing the base layer to a plasma.

In some embodiments, forming the bottom layer comprises a plasma enhanced atomic layer deposition (PEALD) process comprising one or more cycles comprising: providing a substrate to a reaction chamber; exposing the substrate to one or more precursors; flushing excess precursors from the reaction chamber; exposing the substrate to a noble gas plasma comprising reactive species; and flushing excess reactive species from the reaction chamber.

In some embodiments, the lower bottom layer portion has a layered structure comprising alternating silicon-containing layered structures and metal-containing layered structures.

In some embodiments, the lower bottom layer portion includes a metal silicide.

In some embodiments, forming the bottom layer comprises performing a plurality of sub-cycles x and sub-cycles y, wherein sub-cycles x and sub-cycles y are performed alternately, wherein sub-cycle x comprises exposing the substrate to a silicon precursor in a reaction chamber; flushing excess silicon precursor from the reaction chamber; subjecting the substrate to a plasma; and flushing excess reactive species from the reaction chamber; and wherein sub-cycle y comprises exposing the substrate to a metal precursor; flushing excess metal precursor from the reaction chamber; exposing the substrate to a plasma; and flushing excess reactive species from the reaction chamber.

In some embodiments, forming the lower bottom layer portion includes performing a plurality of sub-cycles x and sub-cycles y, and sub-cycles x and sub-cycles y are performed alternately, and sub-cycle x includes exposing the substrate to a silicon precursor in a reaction chamber; flushing excess silicon precursor from the reaction chamber; subjecting the substrate to a plasma; and flushing excess reactive species from the reaction chamber; and sub-cycle y includes exposing the substrate to a metal precursor; flushing excess metal precursor from the reaction chamber; exposing the substrate to a plasma; and flushing excess reactive species from the reaction chamber.

In some embodiments, sub-cycle x) and/or sub-cycle y) comprises using a H ₂ plasma.

In some embodiments, sub-cycle x) and/or sub-cycle y) comprises using an O ₂ plasma.

In some embodiments, sub-cycle x) and/or sub-cycle y) includes using a noble gas plasma.

In some embodiments, sub-cycle x) comprises using an O ₂ plasma and sub-cycle y) comprises using an H ₂ plasma.

In some embodiments, sub-cycle x) comprises using an H ₂ plasma and sub-cycle y) comprises using an O ₂ plasma.

In some embodiments, sub-cycle x) includes using a noble gas plasma and sub-cycle y) includes using an O ₂ plasma.

In some embodiments, sub-cycle x) includes using an O ₂ plasma and sub-cycle y) includes using a noble gas plasma.

In some embodiments, sub-cycle x) includes using a noble gas plasma and sub-cycle y) includes using a H ₂ plasma.

In some embodiments, sub-cycle x) includes using a H ₂ plasma and sub-cycle y) includes using a noble gas plasma.

In some embodiments, sub-cycle x) and/or sub-cycle y) comprises using a N ₂ plasma, NH ₃ plasma, or N ₂ /H ₂ plasma.

In some embodiments, the metal precursor has a general formula M[R( _{CxHy ) n} ] ₄ , wherein M is selected from Ti, Ta, Hf, Zn, and Zr, wherein R is selected from OCH and N, wherein x is 1-2, wherein y is 3-6, and wherein n is 2-3.

In some embodiments, the silane precursor is selected from aminosilanes, alkylsilanes, alkoxysilanes, and silane halides.

In some embodiments, the method further comprises a step of forming a photoresist layer overlying the photoresist base layer.

Further described herein is a structure formed according to the methods described herein.

Further described is a system configured for performing the method as described herein.

In some embodiments, the system includes a first reaction chamber and a second reaction chamber, wherein both the first reaction chamber and the second reaction chamber are configured for depositing a lower bottom layer portion, wherein the second reaction chamber is configured for depositing an upper bottom layer portion, wherein the first reaction chamber operates at a first operating temperature, wherein the second reaction chamber operates at a second operating temperature, and wherein the first operating temperature is higher than the second operating temperature.

In some embodiments, the system includes a third reaction chamber, wherein the third reaction chamber is configured to subject the bottom layer to a thermal or a plasma enhanced post-treatment.

In some embodiments, the second reaction chamber is further configured to subject the bottom layer to a thermal or a plasma enhanced post-treatment.

In some embodiments, the system includes a reaction chamber including a showerhead gas distribution assembly.

In some embodiments, the first reaction chamber and/or the second reaction chamber comprises a showerhead gas distribution assembly.

In some embodiments, the third reaction chamber includes a showerhead gas distribution assembly.

These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of these and other embodiments, which has been prepared with reference to the accompanying drawings; the present invention is not limited to any particular embodiment(s) disclosed.

Although specific embodiments and examples are disclosed below, it will be understood that the invention extends beyond the specifically disclosed embodiments and/or uses thereof and obvious modifications and equivalents thereof. Therefore, it is intended that the scope of the invention disclosed should not be limited to the specific disclosed embodiments described below.

The present disclosure generally relates to methods of forming structures including photoresist bottom layers and structures including photoresist bottom layers. As described in more detail below, exemplary methods may be used to form structures having a photoresist base layer that provide desired properties, such as a desired thickness (e.g., less than 10 or less than 5 nm), relatively low surface roughness, good adhesion to the photoresist, desired etch selectivity, desired thickness uniformity (both within a substrate (e.g., a wafer) and between substrates), high pattern quality (low defect counts and high pattern fidelity), low line width roughness (LWR), stability during EUV lithography processing (e.g., during any post-exposure bake (PEB)), photoresist development, substrate rework, reasonable EUV sensitivity, and compatibility with integration (i.e., other underlying layers should not be damaged under the deposition conditions of the base layer, e.g., not too high a deposition temperature). Further, as discussed below, exemplary embodiments of the present disclosure may be used to tune surface properties (e.g., the values of the polar and dispersive portions of the surface energy of a photoresist base layer) to, for example, promote adhesion between the photoresist base layer and the photoresist layer.

As used herein, the term "substrate" may refer to any underlying material(s) including one or more layers and/or one or more layers may be deposited thereon. A substrate may include a bulk material such as silicon (e.g., single crystal silicon), other Group IV materials such as germanium, or compound semiconductor materials such as GaAs, and may include one or more layers overlying or underlying the bulk material. For example, a substrate may include a patterned stack of layers overlying the bulk material. The patterned stack may vary depending on the application. Further, the substrate may additionally or alternatively include various features such as recesses, lines, and the like formed in or on at least a portion of a layer of the substrate.

In some embodiments, "film" refers to a layer extending in a direction perpendicular to the thickness direction. In some embodiments, "layer" refers to a synonym for a material or a film or non-film structure with a specific thickness formed on a surface. A film or layer may be composed of a discrete single film or layer with specific properties or a plurality of films or layers, and the boundaries between adjacent films or layers may or may not be clear and may or may not be established based on physical, chemical, and/or any other properties, formation processes or sequences, and/or functions or uses of adjacent films or layers. Further, a layer or film may be continuous or discontinuous.

In the present disclosure, "gas" may include materials that are gases at normal temperature and pressure, vaporized solids, and/or vaporized liquids, and may consist of a single gas or a mixture of gases, depending on the context. Gases other than process gases (i.e., gases not introduced through a gas distribution assembly (such as a showerhead), other gas distribution devices, or the like) may be used, for example, to seal reaction spaces, and may include sealing gases such as noble gases.

In some cases (such as in the context of material deposition), the term "precursor" may refer to a compound that participates in a chemical reaction to form another compound, and specifically refers to a compound that constitutes the membrane matrix or the main structure of the membrane, while the term "reactant" may refer to a compound that is different from the precursor in some cases, which activates the precursor, modifies the precursor, or catalyzes the reaction of the precursor; the reactant can provide elements (such as O, N, C) to the membrane matrix and become a part of the membrane matrix. In some cases, the terms precursor and reactant can be used interchangeably. The term "inert gas" refers to a gas that does not participate in chemical reactions to an appreciable extent and/or excite precursors when, for example, RF or microwave power is applied, but unlike the reactants, the inert gas does not become part of the membrane matrix to an appreciable extent.

The term "cyclic deposition process" or "cyclical deposition process" may refer to the sequential introduction of precursors (and/or reactants) into a reaction chamber to deposit a layer above a substrate, and includes processing techniques such as atomic layer deposition (ALD), cyclic chemical vapor deposition (cyclic CVD), and hybrid cyclic deposition processes including ALD and cyclic CVD components.

The term "atomic layer deposition" may refer to a vapor phase deposition process in which a deposition cycle (typically a plurality of consecutive deposition cycles) is performed in a process chamber. When performed using alternating pulses of precursor(s)/reactive(s) gas and purge(s) (e.g., inert carrier) gas, the term atomic layer deposition as used herein is also meant to include processes designated by related terms such as chemical vapor phase atomic layer deposition, atomic layer epitaxy (ALE), molecular beam epitaxy (MBE), gas source MBE, or organometallic MBE, and chemical beam epitaxy.

Typically, for an ALD process, during each cycle, a precursor is introduced into the chamber and chemisorbed onto a deposition surface (e.g., a substrate surface that may include previously deposited material from a previous ALD cycle or other material), forming about a monolayer or sub-monolayer of material that is not readily reactive with additional precursors (i.e., a self-limiting reaction). Thereafter, in some cases, a reactant (e.g., another precursor or a reactive gas) may be subsequently introduced into the chamber for converting the chemisorbed precursor into a desired material on the deposition surface. The reactant is capable of further reacting with the precursor. A purging step may be utilized during one or more cycles (e.g., during each step of each cycle) to remove any excess precursor from the process chamber and/or to remove any excess reactant and/or reaction byproducts from the reaction chamber.

In the present disclosure, any two numbers of a variable may constitute the working range of the variable, and any range indicated may include or exclude the endpoints. In addition, any numerical values of the indicated variables (regardless of whether such numerical values are indicated with "about") may refer to exact values or approximate values and include equivalent values, and in some embodiments may refer to average values, medians, representative values, majority values, etc. Further, in the present disclosure, in some embodiments, the terms "including", "constituted by", and "having" may independently refer to "typically or broadly comprising", "comprising", "consisting essentially of", or "consisting of". According to the aspects of the present disclosure, any defined meanings of the terms do not necessarily exclude the usual and customary meanings of the terms.

Now turning to the drawings, FIG. 1 shows a method 100 according to an exemplary embodiment of the present disclosure. The method 100 includes the following steps: providing a substrate (step 102), forming a photoresist bottom layer (step 104), and depositing a photoresist layer (step 106). The method 100 may also include one or more of forming a carbon-containing layer (step 108) and/or performing a surface treatment (step 110).

Step 102 includes providing a substrate (such as described herein). The substrate may include one or more layers to be etched, including one or more material layers. For example, the substrate may include a deposited oxide, native oxide, or amorphous carbon layer to be etched. The substrate may include several layers underlying the material layer(s) to be etched.

During step 104, a photoresist base layer is formed on the substrate surface. According to an exemplary aspect of method 100, the photoresist base layer is formed using a cyclic deposition process (such as an ALD process). The cyclic deposition process may include the use of activated species (e.g., formed from one or more precursors, reactants, and/or inert gases) formed using one or more of a direct plasma and a remote plasma. Alternatively, step 104 may include a thermal cyclic deposition process. The use of cyclic deposition processes may be desirable because they allow the formation of a photoresist base layer having a desired thickness (e.g., less than 10 nm or less than or approximately equal to 5 nm) with improved thickness uniformity (both within the substrate and between substrates). Use of a plasma enhanced process may be desirable because it allows deposition of the photoresist base material at relatively low temperatures.

According to an example of the present disclosure, the temperature in the reaction chamber during step 104 may be less than 500° C., less than 400° C., less than 300° C., or between about 100° C. and about 500° C., or between about 150° C. and about 300° C. The pressure in the reaction chamber during step 104 may be about 1 Torr to about 100 Torr, about 3 Torr to about 50 Torr, or about 5 Torr to about 20 Torr.

According to exemplary embodiments of the present disclosure, step 104 includes forming or depositing one or more of a metal oxide, a metal nitride, and a metal oxynitride. In some cases, the photoresist underlayer may additionally include carbon. The carbon may be incorporated into the photoresist underlayer as it is deposited and/or a carbon treatment may be applied to the surface of the photoresist underlayer. Additionally or alternatively, a carbon-containing layer or other layer may be deposited on the surface of the photoresist underlayer.

Carbon may be incorporated into the photoresist base layer using one or more precursors including carbon. For example, a cyclic process such as an ALD process may include (A) pulsing a first precursor comprising a metal into a reaction chamber, (B) pulsing a second precursor or reactant comprising an oxidizer and/or a nitrider into the reaction chamber, and (C) pulsing a carbon precursor into the reaction chamber. Each of the pulses may be separated by a rinse step. Further, each pulse step or combination of pulse steps (e.g., pulse steps (A) and (B)) may be repeated several times to tune the amount of carbon in the photoresist base layer before proceeding to the next step. For example, the ratio of (AB):C may range from about 1:1 to about 1:10. Unless otherwise noted, steps (A), (B), and (C) may be performed in any order, and various combinations of steps may be repeated. However, in some cases, it may be desirable to initially form the metal oxide, nitride, or oxynitride by performing one or more cycles of steps (A) and (B), and then perform one or more cycles of step (C). Various combinations of steps (A), (B), and (C) may be performed to obtain a desired concentration gradient throughout the thickness of the photoresist base layer. In some cases, step (C) may be omitted.

According to exemplary aspects of the present disclosure, the first precursor comprising a metal may include a transition metal (such as einsteinium, titanium, aluminum, zirconium, zinc, and the like). The first precursor comprising a metal may also include carbon (e.g., directly or indirectly bonded to one or more organic groups of the metal atom). For specific examples, the first precursor comprising a metal may include a metal halide, or a metal organic compound, or an organometallic compound (such as tetrakis(dimethylamino)titanium (TDMAT), titanium isopropoxide (TTIP), titanium chloride (TiCl), tetrakis(ethylmethylamino)einium (TEMAHf), einsteinium chloride (HfCl), trimethylaluminum (TMA), triethylaluminum (TEA), other metal halides, or one or more of other metal-containing compounds).

According to exemplary embodiments of the present disclosure, the photoresist underlayer comprises metal, oxygen, and carbon. Suitably, such photoresist underlayer may be formed by using a metal-containing precursor, which is provided to the reaction chamber during the step of forming the photoresist underlayer. Suitably, the precursor comprises an alkoxide or alkamide metal precursor. For example, the metal-containing precursor may have the general formula M[R( _{CxHy ) n} ] ₄ , wherein M is selected from Ti, Ta, Hf, Zn, and Zr, wherein R is selected from OCH and N, wherein x is 1 to 2, wherein y is 3 to 6, and wherein n is 2 to 3. Specifically, a titanium-containing precursor having the general formula Ti[R( _{CxHy ) n} ] ₄ may be particularly suitable. Without being bound by theory or any particular mode of operation, it is believed that the precursor ligand can be incorporated into an underlayer (such as an underlayer containing titanium oxycarbide) which can improve the adhesion of the photoresist. Therefore, such an underlayer does not necessarily require the presence of an adhesion layer or glue layer between the metal-containing layer and the subsequently deposited photoresist.

As shown in FIG. 6 , using a pre-grown underlayer having the general formula Ti[R(C _x H _y ) _n ] ₄ allows for better resolution via EUV lithography compared to when a pre-grown underlayer having the general formula TiX ₄ (where X is a halogen such as Cl, I, or F) is used.

The oxidizing agent and/or nitriding agent may include reactants that include one or more of oxygen and nitrogen. In some cases, the reactants may include both nitrogen and oxygen. Also, in some cases, two or more oxidizing agents and/or nitriding agents may be included in a single pulse. Exemplary oxidizing agents and nitriding agents include oxygen (O ₂ ), water (H ₂ O), ozone (O ₃ ), hydrogen peroxide (H ₂ O ₂ ), NH ₃ , diazene (N ₂ H ₂ ), and the like.

The bottom layer described herein can be deposited, for example, using a thermal ALD or thermal CVD method. In this case, an oxidant can be selected as a reactant. For example, the oxidant can be selected from H ₂ O, O ₃ , and H ₂ O _2. Alternatively, the bottom layer described herein can be deposited using plasma ALD or plasma pulsed CVD. Suitable plasmas include H ₂ , H ₂ /He, H ₂ /Ar, Ar, or O ₂ plasma. Both methods can provide suitable for depositing thin (≤ 5 nm) TiO _x C _y with low inhomogeneity.

The carbon precursor may include any suitable organic compound, such as a compound comprising carbon and oxygen. In some cases, the carbon precursor may also include nitrogen. The carbon precursor may be selected to react with, for example, -OH terminated surfaces of metal oxides and/or -NH2 terminated surfaces of metal nitrides. Examples of suitable carbon precursors include one or more of organic compounds such as anhydrides (e.g., acetic anhydride), toluene, diethylene glycol, triethylene glycol, acetaldehyde, and organosilicon compounds such as silanes and siloxanes. Exemplary organic silicon compounds include (n,n-dimethylamino)trimethylsilane, octadecyltrimethoxysilane, hexamethyldisilazane, trimethoxy(3,3,3-trifluoropropyl)silane, trimethoxyphenylsilane, (3,3,3-trifluoropropyl)trichlorosilane, and hexamethyldisilazane.

In general, increasing the ratio and/or number of carbon precursor pulses can increase the amount of carbon in the photoresist base layer. A higher carbon content in the photoresist base layer can affect (e.g., reduce) the polar portion of the surface energy of the photoresist base layer.

The thickness of the photoresist base layer formed during step 104 may be less than 10 nm or less than 5 nm. The carbon content of the photoresist base layer may be greater than 3 at% carbon, greater than 5 at% carbon, greater than 10 at% carbon, or about 5 to about 30 at% carbon. The carbon content may be substantially constant throughout the thickness of the photoresist base layer. Alternatively, the carbon content may vary gradually throughout the thickness of the photoresist base layer. For example, step 104 may end with one or more steps (C) pulsing a carbon precursor into the reaction chamber; and/or including a higher ratio of step (C) relative to steps (A) and (B) near the top surface of the photoresist base layer (e.g., top 1 to 2 nm).

1, method 100 may include forming a carbon-containing layer 108. The carbon-containing layer may be deposited instead of or in addition to incorporating carbon into the photoresist base layer formed during step 104. The carbon-containing layer may be or include, for example, an amorphous carbon layer, a silicon carbon oxycarbon (SiOC) layer, or the like.

As used herein, unless otherwise specified, SiOC is not intended to limit, restrict, or define the bonding or chemical state (e.g., oxidation state) of any of Si, O, C, and/or any other elements in the film. Further, in some embodiments, the SiOC film may include one or more elements (such as H or N) in addition to Si, O, and/or C. In some embodiments, the SiOC film may include Si-C bonds and/or Si-O bonds. In some embodiments, the SiOC film may include Si-C bonds and Si-O bonds, and may not include Si-N bonds. In some embodiments, the SiOC film may include Si-H bonds in addition to Si-C and/or Si-O bonds. In some embodiments, the SiOC film may include more Si-O bonds than Si-C bonds, for example, the ratio of Si-O bonds to Si-C bonds may be from about 1:10 to about 10:1. In some embodiments, the SiOC film may include from about 0% to about 50% carbon by atom. In some embodiments, the SiOC film may include from about 0.1% to about 40%, from about 0.5% to about 30%, from about 1% to about 30%, or from about 5% to about 20% carbon by atom. In some embodiments, the SiOC film may include from about 0% to about 70% oxygen by atom. In some specific examples, the SiOC film may include from about 10% to about 70%, from about 15% to about 50%, or from about 20% to about 40% oxygen by atom. In some embodiments, the SiOC film may include from about 0% to about 50% silicon by atom. In some embodiments, the SiOC film may include from about 10% to about 50%, from about 15% to about 40%, or from about 20% to about 35% silicon by atom. In some embodiments, the SiOC film may include from about 0.1% to about 40%, from about 0.5% to about 30%, from about 1% to about 30%, or from about 5% to about 20% hydrogen by atom. In some embodiments, the SiOC film may not include nitrogen. In some other embodiments, the SiOC film may include from about 0% to about 40% nitrogen by atom (at%). For a specific example, the SiOC film may be or include a layer including SiOCH (such as SiOCNH).

Step 108 may include a cyclic deposition process (such as an ALD process). For example, step 108 may include pulsing a carbon precursor into a reaction chamber, allowing the carbon precursor to react with the substrate surface; and purging any unreacted precursor and/or byproducts. Step 108 may also include providing one or more reactants (such as an oxidant) to the reaction chamber and purging. Step 108 may be a thermal process or a plasma enhanced (direct and/or remote) process. Exemplary carbon precursors suitable for step 108 include any of the carbon precursors mentioned herein.

When the carbon-containing layer comprises SiOC, step 108 may include providing a precursor comprising oxygen, silicon, hydrogen, and at least one organic group. For example, the precursor may include at least one silicon-oxygen bond. Additionally or alternatively, the precursor may include at least one silicon-R bond, wherein R is selected from, for example, one or more of the group consisting of alkyl (e.g., methyl), alkenyl, alkynyl, aryl, alkoxy (e.g., -OCH ₃ , -OCH ₂ CH ₃ ), halogen, and hydrogen. In some cases, the precursor includes at least two organic groups. For example, the precursor may include one or more of dimethyldimethoxysilane, dimethoxytetramethyldisiloxane, octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane (TMCTS), trimethylsilane (3MS), and diethoxymethylsilane (DEMS). The reactant may be selected from one or more of the group consisting of Ar, He, O ₂ , CO ₂ , CO, H 2 , N ₂ O, H ₂ O, N ₂ , and NH _3. During the step of forming the photoresist bottom layer, the temperature in the reaction space may be, for example, between about 20° C. and about 200 _° C. or between about 150° C. and about 350° C. The pressure in the reaction chamber during step 108 may be about 1 Torr to about 100 Torr, about 3 Torr to about 50 Torr, or about 5 Torr to about 20 Torr.

When the carbon-containing layer includes amorphous carbon, step 108 may include deposition via thermal ALD, plasma enhanced (PE) ALD, or PE CVD.

The thickness of the carbon-containing layer may be about 2 to about 3 nm or about 1 to about 2 nm. The carbon concentration in the carbon-containing layer may range from about 50% to 100%, the oxygen concentration in the carbon-containing layer may range from about 0% to about 30%, and the silicon concentration in the carbon-containing layer may range from about 0% to about 30%.

1, method 100 may include a surface treatment (or functionalization) step 110. Surface treatment step 110 may be performed instead of or in addition to either or both of incorporating carbon into the photoresist underlayer as the photoresist underlayer is formed and forming the carbon-containing layer (step 108).

In some cases, step 110 includes treating with a reactant (e.g., a halogenated gas such as fluorine or chlorine) to, for example, change the dispersive and/or polar portion of the surface energy of the photoresist layer. The reactant may be activated thermally or using a plasma (e.g., direct or remote plasma).

In some cases, step 110 may include treatment with one or more carbon-containing agents. Exemplary carbon-containing agents include any of the carbon precursors mentioned herein.

According to a further embodiment of the present disclosure, a silanizing agent may be used to treat the substrate surface during step 110. Exemplary silanizing agents may include silicon and one or more organic groups. For example, suitable silanizing agents may include silicon bonded to one or more organic (e.g., methyl, oxymethyl, or the like) groups and/or silicon bonded to nitrogen (e.g., nitrogen atoms bonded to one or more silicon atoms). The silanizing agent may include a silane compound having a hydrolyzable anchor group (e.g., methoxy/ethoxy/Cl, F, or the like). For example, step 110 may include exposing the substrate surface (e.g., the surface of the photoresist bottom layer formed during step 104) to a silanizing agent selected from the group consisting of dimethylaminotrimethylsilane (DMA-TMS), hexamethyldisilazane (HMDS), (3-bromopropyl)trimethoxysilane, (3-iodopropyl)trimethoxysilane, 3-(trimethoxysilyl)propyl acrylate, trimethoxyphenylsilane, trimethoxy(3,3,3-trifluoropropyl)silane, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, ti-chlorophenylsilane, and trimethoxy( 1H , 1H , 2H , 2H -heptadecafluorodecyl)silane (FTMS).

The self-assembled (e.g., single) layer can also be used to treat or functionalize the surface of a photoresist bottom layer. In these cases, step 110 may include exposing the substrate surface (e.g., the surface of the photoresist bottom layer formed during step 104) to a suitable precursor. Exemplary precursors suitable for forming a self-assembled monolayer during step 110 include organic and organosilicon compounds (e.g., compounds including one or more of silicon and carbon (e.g., Si-C bonds)) (e.g., silanes and siloxanes), such as compounds selected from the group consisting of perfluorodecyltrimethoxysilane (PFDTMS), tetramethoxysilane (TMOS), trimethoxy(octadecyl)silane (TMODS), trimethoxy(3,3,3-trifluoropropyl)silane, triethoxyphenylsilane, trichloro(phenyl)silane, other silicon- and carbon-containing compounds described herein, and the like.

The temperature in the reaction chamber during step 110 may be less than 500° C., less than 400° C., less than 300° C., or between about 100° C. and about 500° C., or between about 150° C. and about 300° C. The pressure in the reaction chamber during step 110 may be about 1 Torr to about 100 Torr, about 3 Torr to about 50 Torr, or about 5 Torr to about 20 Torr, or from about 1 Torr to about 4 Torr, or from about 2 Torr to about 6 Torr.

During step 106, a photoresist layer is deposited overlying the photoresist base layer. The photoresist may be deposited using, for example, a spin-on technique. The photoresist layer may be or include a positive or negative extreme ultraviolet (EUV) lithography photoresist.

FIG. 2 shows a structure 200 according to an exemplary embodiment of the present disclosure. The structure 200 can be formed using the method 100, for example.

As shown, structure 200 includes substrate 202, material layer 204, photoresist underlayer 206, and photoresist layer 208. As shown, structure 200 may optionally include one or more of carbon-containing layer 210 and/or treated surface 212.

The substrate 202 may include a substrate as described above. For example, the substrate 202 may include a semiconductor substrate (such as a bulk material, such as silicon (e.g., single crystal silicon)), other Group IV semiconductor materials, Group III-V semiconductor materials, and/or Group II-VI semiconductor materials, and may include one or more layers (e.g., a patterned stack) overlying the bulk material. Further, as mentioned above, the substrate 202 may include various topography, such as recesses, lines, and the like formed in or on at least a portion of a layer of the substrate.

Material layer 204 may be patterned and etched using a photoresist base layer and a photoresist layer as described herein. Exemplary materials suitable for material layer 204 include, for example, oxides such as native oxides or field oxides. Other exemplary materials for material layer 204 include amorphous carbon, nitrides, other oxides, silicon, and additional films such as self-assembled monolayers such as hexamethyldisilazane (HMDS).

The photoresist base layer 206 may include a photoresist base layer formed according to the methods described herein (e.g., method 100) and/or have properties as described herein. Exemplary photoresist base layers include one or more of metal oxides, metal nitrides, and metal oxynitrides. In some cases, the photoresist base layer 206 may include added carbon, as mentioned above. For example, the photoresist base layer 206 may have a carbon concentration and/or a carbon concentration gradient as mentioned herein.

The thickness of the photoresist base layer 206 may depend on the composition of the material layer 204, the thickness of the material layer 204, the photoresist type, and the like. According to examples of the present disclosure, the photoresist base layer 206 has a thickness of less than 10 nm or less than or about 5 nm. If the photoresist base layer 206 is too thick, residual base material may remain after the etching step. If the photoresist base layer 206 is too thin, the photoresist base layer 206 may not provide a desired pattern transfer during the etching process. The surface of the photoresist base layer 206 (or the carbon-containing layer thereon) may or may not be treated with a treatment step (e.g., step 110) to provide a desired surface termination, for example, to promote adhesion with the photoresist layer 208.

The photoresist base layer 206 desirably exhibits good adhesion and other properties as described herein. To provide the desired adhesion between the photoresist layer 208 and the photoresist base layer 206, the photoresist base layer 206 may have or be tuned to have desired surface chemical properties, for example, quantified as surface energy, which is further classified into a surface energy polar portion and a surface energy dispersive portion. The surface energy polar portion and surface energy _dispersive portion of the photoresist base layer 206 can be calculated by measuring the contact angle of a liquid (such as water or _CH2I2 ) and using the Owens, Wendt, Rabel, and Kaelble (OWRK) method to determine the surface energy polar portion and the dispersive portion. The same properties can be measured and calculated for the photoresist layer 208.

According to various embodiments of the present disclosure, the polar portion of the surface energy of the photoresist bottom layer has a value between about 5 mN/m and about 25 mN/m, or between about 20 mN/m and about 40 mN/m. According to further embodiments, the dispersive portion of the surface energy of the photoresist bottom layer has a value between about 10 mN/m and about 30 mN/m, or between about 5 mN/m and about 25 mN/m, or between about 20 mN/m and about 40 mN/m. For example, when the photoresist layer 208 comprises a negative photoresist, the value of the polar portion of the surface energy of the photoresist bottom layer may be between about 20 mN/m and about 40 mN/m, and/or the value of the dispersive portion of the surface energy of the photoresist bottom layer may be between about 10 mN/m and about 30 mN/m or between about 20 mN/m and about 40 mN/m. When the photoresist layer 208 comprises a positive photoresist, the value of the polar portion of the surface energy of the photoresist bottom layer may be between about 5 mN/m and about 25 mN/m, and/or the value of the dispersive portion of the surface energy of the photoresist bottom layer may be between about 10 mN/m and about 30 mN/m.

Carbon-containing layer 210 may include a carbon-containing layer (such as a carbon-containing layer described herein). Exemplary carbon-containing layers include amorphous carbon and/or SiOC layers. Layer 210 may have a thickness of less than 5 nm or less than 2 nm. For example, carbon-containing layer 210 may be about 1 to about 1.5 nm thick.

The treated (or functionalized) surface 212 may include any surface that has been exposed to a treatment process, such as treatment step 110. For example, the treated surface may include a silanized surface and/or a surface comprising a self-assembled layer, as described herein.

FIG3 shows a structure 300 according to a further exemplary embodiment of the present disclosure. Structure 300 is similar to structure 200 except that structure 300 does not include a carbon-containing layer or a photoresist layer.

Structure 300 includes substrate 302, material layer 304, and photoresist underlayer 306. Substrate 302 may be the same as or similar to substrate 202. Likewise, material layer 304 may be the same as or similar to material layer 204. Photoresist underlayer 306 may be the same as or similar to photoresist underlayer 206. However, in the case where structure 300 does not include a carbon-containing layer, photoresist underlayer 306 may include a relatively high amount of carbon (e.g., greater than 5 at% or about 5 at% to about 30 at% carbon). Structure 300 may be desirable because structure 300 may be formed using relatively few process steps. Further, the carbon concentration in the photoresist base layer 306 can be easily tuned (eg, by manipulating the ratio of the carbon deposition step relative to other deposition steps).

FIG4 shows a structure 400 according to a further exemplary embodiment of the present disclosure. Structure 400 is similar to structure 200 except that structure 400 does not include a photoresist layer and in some cases may not include a treated surface.

Structure 400 includes substrate 402, material layer 404, photoresist underlayer 406, and carbon-containing layer 408. Substrate 402 may be the same as or similar to substrate 202. Likewise, material layer 404 may be the same as or similar to material layer 204. Photoresist underlayer 406 may be the same as or similar to photoresist underlayer 206. However, because structure 400 includes carbon-containing layer 408, photoresist underlayer 406 may include a relatively low amount of carbon (e.g., less than 5 at% or less than 10 at%). Carbon-containing layer 408 may include any carbon-containing layer described herein, and may optionally be treated. Structure 400 may be desirable for some applications because photoresist bottom layer 406 may be or may include a typical metal oxide, nitride, or oxynitride layer (e.g., without added carbon). In other words, an additional step of incorporating carbon into photoresist bottom layer 406 may not be used.

FIG5 shows a structure 500 according to a further exemplary embodiment of the present disclosure. The structure 500 is similar to the structure 200 except that the structure 500 does not include a photoresist layer and does not include the carbon-containing layer 210.

Structure 500 includes substrate 502, material layer 504, photoresist bottom layer 506, and treated surface 508. Substrate 502 may be the same as or similar to substrate 202. Material layer 504 may be the same as or similar to material layer 204. Bottom layer 506 may be the same as or similar to photoresist bottom layer 206. However, because structure 500 does not include a carbon-containing layer, bottom layer 506 may include a relatively high amount of carbon (e.g., greater than 5 at%, from about 5 at% to about 30 at%). As described herein, treated surface 508 may include material from one or more of a silanizer and/or a self-assembly precursor. Structure 500 may be desirable because the surface treatment allows very thin, self-limiting materials to be used for treated surface 508. Furthermore, a wide variety of surface treatment agents may be used to form the treated surface 508.

In some cases, the photoresist base layer or a layer or treated surface thereon may be exposed to a post-deposition treatment step including plasma formation. In these cases, the plasma treatment step may include exposing the photoresist base layer to species activated using direct and/or remote plasma. The plasma treatment step may include forming the activated species from a gas including _one or more of _H2 , _O2 , _CO2 , CO, _N2O , _NF3 , and _CxHyFz , where x>=1, y _> =0, and z>=0. Such treatment may be used, for example, to further tune the dispersive and/or polar portions of the surface energy to desired values.

Although not shown, methods according to the present disclosure may include determining the surface energy properties of the photoresist base layer and/or the photoresist layer. For example, the method may include determining one or more of the dispersive portion and the polar portion of the surface energy of one or more of the photoresist layer and the photoresist base layer. The method may further include selecting the photoresist base layer material based on one or more of the dispersive portion and the polar portion of the surface energy of the photoresist layer; and/or tuning based on more of the dispersive portion and the polar portion of the surface energy of the photoresist base layer (e.g., using techniques as described herein).

A system (700) configured for performing the method as described herein is now further described with reference to FIG. 7. The system comprises at least one reaction chamber configured for depositing a bottom layer as described herein. The system may comprise a first reaction chamber (711) and a second reaction chamber (712), both of which may be configured for depositing a bottom layer as described herein or a portion thereof. Suitably, the first reaction chamber (711) operates at an operating temperature higher than the operating temperature of the second reaction chamber (712). Such a multi-chamber approach may be advantageous in maximizing the corrosion resistance of the metal-containing bottom layer. Specifically, the first reaction chamber (711) operated at a higher temperature can be used to deposit a pure and dense metal oxide with high corrosion resistance, and the second reaction chamber (712) operated at a lower temperature can be suitably used to deposit a metal oxide with good adhesion to the photoresist. Without being bound by any specific theory or mode of operation, it is believed that this is due to the increased incorporation of precursor ligands into the bottom layer at a lower deposition temperature relative to a higher deposition temperature.

Optionally, the second reaction chamber (712) is further configured to subject the bottom layer to a thermal or plasma enhanced post-treatment. Alternatively, the system (700) may include a third reaction chamber (713) in which a thermal or plasma enhanced post-treatment may be performed. The post-treatment may employ, for example, _H2 , _H2 /He, _H2 /Ar, Ar, and/or _O2 plasma.

In a specific example embodiment, the bottom layer is deposited using a thermal ALD process. Titanium (IV) isopropoxide may be used as a precursor, and a mixture of _H2O and _O3 may be used as a co-reactant. The precursor and reactant are provided to the reaction chamber in an alternating pulse cycle. Suitable process temperatures include a range of 70°C to 300°C. Process temperatures below 200°C advantageously improve adhesion to the photoresist, which is believed to be related to the incorporation of precursor ligands and/or isopropanol byproducts without being bound by theory or a specific mode of operation of the present invention. Process temperatures above 200°C advantageously provide increased corrosion resistance.

In a specific example embodiment, the bottom layer is deposited using another thermal ALD process. Tetrakis(dimethylamino)titanium can be used as a precursor, and a mixture of _H2O and _O3 can be used as a co-reactant. The precursor and reactant are provided to the reaction chamber in an alternating pulse cycle. Suitable process temperatures include a range of 70°C to 300°C, and can produce _TiO2 -containing films with superior properties. Process temperatures below 200°C advantageously improve adhesion to the photoresist, which is believed to be related to the incorporation of the precursor ligand into the bottom layer without being bound by theory or a specific mode of operation of the present invention. Process temperatures above 200°C advantageously provide increased corrosion resistance.

FIG. 8 shows a structure (800) formed using a particular embodiment of the present methods, which include forming a lower bottom layer portion (811) and an upper bottom layer portion (812) on a substrate (810). The substrate (810) may include a silicon wafer and optionally one or more patterned features and/or material layers. For example, the substrate (810) may include one or more layers underlying a photoresist bottom layer, as shown in any of the other figures contained herein.

In some embodiments, the lower bottom layer portion comprises a metal oxide (e.g., titanium oxide) and the upper bottom layer portion comprises carbon. In such embodiments, the lower bottom layer portion may have a thickness of, for example, from at least 1.0 to at most 5.0 nm or from at least 2.0 to at most 3.0 nm. Similarly, the upper bottom layer portion may have a thickness of, for example, from 0.1 nm to at most 2.0 nm or from at least 0.5 nm to at most 1.0 nm.

The lower bottom layer portion may be formed using a metal halide precursor (e.g., chloride, fluoride, bromide, or iodide of Hf, Ti, Ta, _Zn , or Zr). The upper bottom layer portion may be formed using a metal-containing precursor having the general formula M[R( _CxHy ) _n ] ₄ , wherein M is selected from Ti, Ta, Hf, Zn, and Zr, wherein R is selected from OCH and N, wherein x is 1 to 2, wherein y is 3 to 6, and wherein n is 2 to 3. Such a double-layer bottom layer structure may be particularly advantageous because it may combine the good corrosion resistance of the lower bottom layer portion with the suitable surface properties provided by the upper bottom layer portion.

Additionally or alternatively, the upper bottom layer portion may include silicon, oxide, and carbon. In such embodiments, the upper bottom layer portion may have a thickness of, for example, from at least 0.1 nm to at most 2.0 nm (e.g., a thickness of 0.2 nm, 0.4 nm, 0.6 nm, 0.8 nm, 1.0 nm, or 1.5 nm). Such a bottom layer may be formed, for example, by an ALD or CVD process using, for example, a thermal or plasma enhanced process with an organic silicon precursor and an oxygen reactant such as O ₂ , H ₂ O, O ₃ , or H ₂ O ₂ .

The application of a noble gas plasma (such as Ar plasma) for the deposition of the upper bottom layer portion is particularly advantageous. Without wishing to be bound by any theory or specific mode of operation, it is believed that this is due to the presence of precursor ligands in the layer thus formed, which results in superior adhesion properties.

The upper bottom layer portion can be formed using either plasma enhanced atomic layer deposition (PEALD) or pulsed plasma enhanced chemical vapor deposition (pulsed PECVD). In the PEALD mode, a precursor can be introduced into a reaction chamber containing a substrate, react with surface reactive sites, and then chemically adsorbed on the substrate surface. In a second step, excess precursor can be partially or completely flushed from the reaction chamber to avoid, minimize, or reduce CVD reactions. In a third step, the substrate can be exposed to a rare gas plasma (e.g., Ar, He, Ne, Kr, or Xe plasma). In a fourth step, the plasma power is continuously turned off for a predetermined amount of time to flush at least a portion of the reactive species from the reaction chamber. This process can be repeated any number of times to obtain an upper bottom layer portion. Advantageously, such an upper bottom layer portion contains a metal-containing layer (e.g., a metal oxide) having a high carbon content (e.g., a carbon content of at least 10 atomic % to at most 70 atomic %, or at least 20 atomic % to at most 60 atomic %, or at least 30 atomic % to at most 50 atomic %, or about 40 atomic %). The upper bottom layer portion can suitably serve as an adhesion layer or glue to a subsequently deposited photoresist layer.

Alternatively, in some embodiments, the upper bottom layer portion may be deposited using pulsed plasma enhanced chemical vapor deposition (pulsed PECVD). In one exemplary pulsed PECVD process for depositing the upper bottom layer portion, the substrate may be exposed to a rare gas plasma (e.g., Ar, He, Ne, Kr, or Xe plasma). Thereafter, the substrate may be exposed to a metal precursor while the plasma remains on such that the precursor dissociates through the action of the plasma. Thus, a carbon-containing metal layer (e.g., a carbon-containing metal oxide layer) may be formed on the substrate. Thereafter, the supply of the metal precursor is stopped. Optionally, the plasma remains on for a predetermined amount of time (e.g., 1.0 seconds to 60 seconds, or 2.0 seconds to 30 seconds, or 4.0 seconds to 15 seconds, or 6 seconds to 12 seconds). Without being bound by theory or a specific mode of operation, it is believed that keeping the plasma on after the metal precursor flow has stopped can advantageously modify the surface properties of the deposited layer. By the pulsed PECVD process described above, an upper bottom layer portion (e.g., a C-rich MOx adhesion layer) can be formed. When used in conjunction with a suitable EUV photoresist, it provides an improved process window to resist pattern collapse and lower line edge roughness (LER) and line width roughness (LWR).

It is noted that suitable precursors for depositing the upper substrate portion via pulsed PECVD or PEALD include the metal precursors mentioned herein.

In some embodiments, the substrate may be subjected to a surface treatment (e.g., a surface treatment resulting in a surface termination). The surface treatment may be applied to both a one-piece substrate and a substrate comprising a lower substrate portion and an upper substrate portion. Such a surface treatment may eliminate the need for an upper substrate portion, or it may be used to treat the surface of the upper substrate portion.

Exemplary surface treatments use organic silicon compounds such as silane amines. Exemplary organic silicon compounds include alkylaminosilylamines and/or alkylsilylamines such as bis(tripropylsilyl)amine, bis(triethylsilyl)amine, bis(trimethylsilyl)amine, (dimethylamino)trimethylsilane, (diethylamino)trimethylsilane, (diethylamino)triethylsilane, and (dimethylamino)triethylsilane. Additionally or alternatively, the surface treatment may include the use of fluoroalkyl substituted silanes. Such fluorine-containing molecules can be used to reduce the surface energy of the underlying layer to disperse the portion. Additionally or alternatively, the surface treatment may include the use of halogen substituted silanes and/or alkoxysilanes such as methoxysilane or ethoxysilane. Additionally or alternatively, the surface treatment may comprise using a compound selected from the list consisting of (3-bromopropyl)trimethoxysilane, (3-iodopropyl)trimethoxysilane, 3-(trimethoxysilyl)propyl acrylate, trimethoxyphenylsilane, trimethoxy(3,3,3-trifluoropropyl)silane, and 1H,1H,2H,2H-perfluorooctyltriethoxysilane.

Additionally or alternatively, the surface treatment may include subjecting the underlying layer to a noble gas plasma (e.g., Ar, He, Ne, Kr, or Xe plasma).

This type of surface treatment allows for proper control of the surface energy of the underlying layer for improved photoresist adhesion.

Another possible surface treatment that may be performed in addition to or instead of other surface treatments mentioned herein includes subjecting the bottom layer to a plasma (e.g., H plasma, Ar/H plasma (i.e., a plasma comprising Ar and H), or He/H plasma (i.e., a plasma comprising He and H)). Subjecting the bottom layer to such a plasma may result in the formation of CH3 and/or CH2 functional groups on the bottom layer surface. Additionally or alternatively, the bottom layer may be subjected to a halogen-containing plasma (e.g., a fluorine-containing plasma, such as a _CF4 plasma), which may result in the formation of a fluorine-terminated surface of the bottom layer. Additionally or alternatively, the bottom layer may be subjected to a chlorine-containing plasma (e.g., a _Cl2 plasma), which may result in the formation of a chlorine-terminated surface of the bottom layer.

Thus, the surface properties of the underlying layer can be modified by i) variations in the deposition process (ALD/CVD) and/or ii) post-treatment (e.g., plasma-based post-treatment). Without being bound by theory or any specific mode of operation, it is believed that the carbon concentration in the underlying layer primarily affects the surface polarity, while the presence of various elements (e.g., H, F, Cl from the plasma) ultimately affects the surface energy.

FIG. 9 shows an exemplary process flow for a bottom layer, a lower bottom layer portion, and/or an upper bottom layer portion deposited by plasma enhanced chemical vapor deposition. During the process, a substrate in a reaction chamber is exposed to one or more precursors. Afterwards, excess precursors can be flushed from the reaction chamber. Thereafter, the substrate can be subjected to a plasma. For example, in order to produce an upper bottom layer portion with good adhesion properties, a rare gas plasma (e.g., He, Ne, Ar, Kr plasma) can be used. After the plasma step, excess reactive species (such as ions and free radicals) are flushed from the reaction chamber in a suitable manner. The aforementioned steps form a cycle. These cycles may be repeated any number of times to deposit a base layer or portion thereof having the desired thickness.

In an exemplary process, both the lower bottom layer portion and the upper bottom layer portion are formed using a plasma enhanced chemical vapor deposition process. Exemplary, non-limiting process conditions for forming a lower bottom layer portion comprising titanium oxide include a precursor feed time of 0.4 seconds, a precursor purge time of 0.7 seconds, the precursor is carried by an Ar carrier gas, the flow rate of the Ar carrier gas is 1 slm, additionally, a continuous flow of argon of 1 slm is provided as a plasma gas, O ₂ is used as a reactant, the flow rate of O ₂ is 2 slm, the plasma power is 100 W, the plasma on time is 0.2 seconds, the post plasma purge time is 0.1 seconds, the electrode gap is 12 mm, the pressure is 400 Pa, the susceptor temperature is 190° C., and the lower bottom layer portion is formed in 31 cycles, resulting in a 2.45 nm thickness. Exemplary, non-limiting process conditions for forming the upper bottom layer portion comprising titanium oxide include: a precursor feed time of 0.4 seconds, a precursor flush time of 0.7 seconds, the precursor is carried by an Ar carrier gas, the flow rate of the Ar carrier gas is 1 slm, additionally, a continuous flow of argon of 1 slm is provided as a plasma gas, the plasma power is 50 W, the plasma on time is 2.2 seconds, the post plasma flush time is 0.1 seconds, the electrode gap is 7.5 mm, the pressure is 900 Pa, the susceptor temperature is 190°C, and the upper bottom layer portion is formed in 15 cycles, resulting in a thickness of 0.5 nm. This example is given for the formation of an underlayer on a substrate comprising a carbon hard mask. Such a combination of a lower underlayer portion and an upper underlayer portion allows obtaining an underlayer having good corrosion resistance and good adhesion to the photoresist. Furthermore, the upper underlayer portion can protect the layers covered by the underlayer (such as carbonaceous layers, e.g., diamond-like carbon layers, amorphous carbon layers, or the like). Additionally, the use of the upper underlayer portion can advantageously improve the density of the lower underlayer portion.

It should be understood that the lower bottom layer portion and/or the upper bottom layer portion may be deposited using deposition conditions different from the exemplary process conditions described above. For example, the lower bottom layer portion and/or the upper bottom layer portion may be deposited at a temperature from at least 70° C. to at most 300° C. As another example, the lower bottom layer portion and/or the upper bottom layer portion may be deposited at a pressure of at least 100 Pa to at most 800 Pa, or at a pressure of at least 200 Pa to at most 600 Pa.

In some embodiments, the base layer, either in one piece or consisting of a lower base layer portion and an upper base layer portion, is deposited using thermal atomic layer deposition as opposed to plasma enhanced atomic layer deposition. In such embodiments, it may be particularly advantageous to subject the base layer to a plasma (e.g., a noble gas plasma) after the base layer has been deposited. Such post-treatment may advantageously densify the base layer.

FIG. 10 shows yet another exemplary embodiment of a structure (1000) comprising a lower bottom layer portion and an upper bottom layer portion (1020) disposed on a substrate (1010). The upper bottom layer portion (1020) is described in detail elsewhere herein. The lower bottom layer portion has a layered structure comprising alternating silicon oxide layered structures (1011) and metal oxide layered structures (1012).

FIG. 11 shows yet another exemplary embodiment of a structure (1100) comprising a lower bottom layer portion (1111) and an upper bottom layer portion (1112) disposed on a substrate (810). The lower bottom layer portion (1111) comprises a metal silicate. The upper bottom layer portion (1112) is described in detail elsewhere herein.

FIG. 12 shows a flow chart of an exemplary embodiment of a method for forming a bottom layer as described herein, illustrated with three process flows a, b, and c. Each of process flows a, b, and c includes sub-cycles x and y, which are combined to form a super-cycle z. Super-cycle z can be repeated multiple times to obtain a bottom layer with a desired thickness (e.g., a thickness of about several nm). Similarly, given that sub-cycle x is shown in FIG. 12 as preceding sub-cycle y, and although this order as shown is one possible solution, the order of sub-cycle y and sub-cycle x can be reversed in some embodiments. It should be further understood that sub-cycles x and y can be performed in the same reaction chamber. Alternatively, they may be performed in different reaction chambers contained in a larger system.

When no significant mixing of the formed layer structures occurs, any of process flows a), b), or c) can result in the formation of a laminate made of alternating silicon-containing layer structures and metal-containing layer structures, as shown in Figure 10. Alternatively, when mixing does occur (e.g., via diffusion), any of process flows a), b), or c) can result in a layer comprising silicon, metal, and optionally one or more additional elements. This layer can then be used as a bottom layer by itself. Alternatively, it can be used as a lower bottom layer portion, combined with an upper bottom layer portion as described herein. Such layers are highly effective and can be used to minimize or even eliminate the problem of protruding feet during EUV photoresist patterning.

Process flows a), b), and c) each include two sub-cycles, sub-cycle x) and sub-cycle y). Sub-cycle x) includes exposing the substrate to a silicon precursor in a reaction chamber; flushing excess silicon precursor from the reaction chamber; subjecting the substrate to plasma; and flushing excess reactive species from the reaction chamber. Therefore, sub-cycle x) can appropriately form a silicon oxide layered structure. Sub-cycle y) includes exposing the substrate to a metal precursor; flushing excess metal precursor from the reaction chamber; exposing the substrate to plasma; and flushing excess reactive species from the reaction chamber.

As shown in FIG. 12 , the differences between process flows a), b), and c) lie in the plasma used in sub-cycles x) and y). Specifically, in process flow a), O ₂ plasma is used in both sub-cycles x) and y). In process flow b), H ₂ plasma is used in both sub-cycles x) and y). In process flow c), a rare gas plasma such as Ar plasma is used in both sub-cycles x) and y). Of course, other combinations are also possible, for example, in some embodiments, sub-cycle x) includes the use of O ₂ plasma, and sub-cycle y) includes the use of H ₂ plasma. Alternatively, in some embodiments, subcycle x) comprises the use of a noble gas plasma, and subcycle y) comprises the use of an O ₂ plasma. Alternatively, in some embodiments, subcycle x) comprises the use of an O ₂ plasma, and subcycle y) comprises the use of a noble gas plasma. Alternatively, in some embodiments, subcycle x) comprises the use of a noble gas plasma, and subcycle y) comprises the use of an H ₂ plasma. Alternatively, in some embodiments, subcycle x) comprises the use of an H ₂ plasma, and subcycle y) comprises the use of a noble gas plasma.

Alternatively, _N plasma, _NH plasma, or N/ _H plasma (i.e., a plasma fed with a plasma gas consisting essentially of _N and _H ) can also be used in subcycles x) and/or y). Thus, depending on the precursors used, SiN, or SiON, or SiCN can be deposited in subcycle x), and metal _nitrides , metal oxynitrides, and/or metal carbonitrides can be deposited in subcycle y). As before, this can result in either a bottom layer or a portion thereof comprising a separate layered structure or a mixture of the aforementioned compounds, depending on the amount of intermixing during or after deposition. Thus, in some embodiments, subcycle x) comprises the use of N ₂ , NH ₃ , or N ₂ / H ₂ plasma, and subcycle y) comprises the use of H ₂ plasma. Alternatively, in some embodiments, subcycle x) comprises the use of H ₂ plasma, and subcycle y) comprises the use of N ₂ , NH ₃ , or N ₂ / H 2 plasma. Alternatively, in some embodiments, subcycle x) comprises the use of O ₂ plasma, and subcycle y) comprises the use of N ₂ , NH ₃ , or N ₂ / H ₂ plasma. Alternatively, in some embodiments, subcycle x) comprises the use of N ₂ , NH ₃ , or N ₂ / H ₂ plasma, and subcycle y) comprises the use of O ₂ plasma. Alternatively, in some embodiments, subcycle x) comprises the use of a noble gas plasma, and subcycle y) comprises the use of N ₂ , NH ₃ , or N ₂ /H ₂ plasma. Alternatively, in some embodiments, subcycle x) comprises the use of N ₂ , NH ₃ , or N ₂ /H ₂ plasma, and subcycle y) comprises the use of a noble gas plasma. Alternatively, in some embodiments, subcycle x) comprises the use of N ₂ plasma, and subcycle y) comprises the use of N ₂ , NH ₃ , or N ₂ /H ₂ plasma. Alternatively, in some embodiments, subcycle x) comprises the use of N ₂ , NH ₃ , or N ₂ /H ₂ plasma, and subcycle y) comprises the use of N ₂ plasma. Alternatively, in some embodiments, subcycle x) comprises the use of NH ₃ plasma, and subcycle y) comprises the use of N ₂ , NH ₃ , or N ₂ /H ₂ plasma. Alternatively, in some embodiments, subcycle x) comprises the use of N ₂ , NH ₃ , or N ₂ /H ₂ plasma, and subcycle y) comprises the use of NH ₃ plasma. Alternatively, in some embodiments, subcycle x) comprises the use of N ₂ /H ₂ plasma, and subcycle y) comprises the use of N ₂ , NH ₃ , or N ₂ /H ₂ plasma. Alternatively, in some embodiments, sub-cycle x) comprises using N ₂ , NH ₃ , or N ₂ /H ₂ plasma, and sub-cycle y) comprises using N ₂ /H ₂ plasma.

The silane precursor may be, for example, an organic silane (such as an aminosilane, an alkylsilane, or an alkoxysilane). Alternatively, the silane precursor may include a silane halide (such as a chlorosilane or an iodosilane). Exemplary silane precursors include bisdiethylaminosilane (BDEAS), bisisopropylaminosilane (DIPAS), N-methyl-aza-2,2,4-trimethylsilacyclopentane, hexamethyldisilazane (HMDS), 3-aminopropyltrimethoxysilane (APTMS), and 3-methoxypropyltrimethoxysilane (MPTMS), dimethyldimethoxysilane (DMDMOS), dimethoxytetramethyldisiloxane (DMOTMDS), and octamethylcyclotetrasiloxane (OMCTS), diiodosilane, and dichlorosilane. Experimental results indicate that N-methyl-aza-2,2,4-trimethylsilacyclopentane gave a growth rate of 0.06 nm/cycle using oxygen plasma and at a temperature of 300°C. In addition, HMDS gave a growth rate of 0.025 nm/cycle, APTMS gave a growth rate of 0.063 nm/cycle, and MPTMS gave a growth rate of 0.039 nm/cycle using oxygen plasma and a temperature of 100°C. Thus, subcycle x) can be performed at a temperature of at least 50°C to at most 400°C (e.g., at a temperature of at least 70°C to at most 300°C or at a temperature of at least 100°C to at most 200°C).

Subcycle y may utilize, for example, a metal halide precursor (e.g., chloride, fluoride, bromide, or iodide of Hf, Ti, Ta, _Zn , or Zr). Alternatively, subcycle y) may utilize a metal-containing precursor having the general formula M[R( _CxHy ) _n ] ₄ , wherein M is selected from Ti, Ta, Hf, Zn, and Zr, wherein R is selected from OCH and N, wherein x is 1 to 2, wherein y is 3 to 6, and wherein n is 2 to 3. Exemplary metal precursors for use in subcycle y include metal alkoxides and metal amides. For example, when the metal is titanium, suitable precursors include titanium tetraisopropoxide (TTIP) and titanium tetrakis(dimethylamido) (TDMAT). For example, TTIP and TDMAT can be used to deposit TiO ₂ using O ₂ plasma with growth rates of 0.4 and 0.6 Å/cycle, respectively, at 190°C.

The exemplary embodiments of the present disclosure described above do not limit the scope of the present invention, as these embodiments are merely examples of embodiments of the present invention. Any equivalent embodiments are intended to be within the scope of the present invention. In fact, in addition to the embodiments shown and described herein, a person with ordinary knowledge in the art will be able to understand various modifications of the present disclosure (e.g., alternative combinations of the components described) from this specification. Such modifications and specific examples are also intended to be within the scope of the attached patent application.

100: Method 102,104,106,108,110: Steps 200,300,400,500,800,1000,1100: Structure 202,302,402,502,810: Substrate 204,304,404,504: Material layer 206,306,406,506: Photoresist base layer 208: Photoresist layer 210,408: Carbon-containing layer 212, 508: treated surface 700: system 711: first reaction chamber 712: second reaction chamber 713: third reaction chamber 811,1111: lower bottom layer 812,1112: upper bottom layer 1011: silicon oxide layer 1012: metal oxide layer 1020: including lower bottom layer and upper bottom layer a,b,c: process flow x,y: sub-cycle z: super-cycle

A more complete understanding of the exemplary embodiments of the present disclosure may be obtained by referring to the embodiments and claims when considered in conjunction with the following illustrative drawings. FIG. 1 illustrates a method of forming a structure according to an exemplary embodiment of the present disclosure. FIG. 2 illustrates a structure according to an exemplary embodiment of the present disclosure. FIG. 3 illustrates a structure according to an exemplary embodiment of the present disclosure. FIG. 4 illustrates another structure according to an exemplary embodiment of the present disclosure. FIG. 5 illustrates yet another structure according to an exemplary embodiment of the present disclosure. FIG. 6 shows experimental results indicating that using a pre-drive grown bottom layer having the general formula Ti[R( _CxHy ) _n ] ₄ allows for better resolution via EUV lithography compared to when using a pre-drive grown bottom layer having the general formula _TiX4 (where _X is a halogen such as Cl, I, or F). FIG. 7 shows a system (700) configured for performing the method as described herein. FIG. 8 shows a structure (800) formed using a specific embodiment of the method. FIG. 9 shows an exemplary process flow for depositing a bottom layer. FIG. 10 shows an exemplary embodiment of a structure (1000) comprising a lower bottom layer portion and an upper bottom layer portion (1020). FIG. 11 shows an embodiment of a structure (1100) comprising a lower substrate portion (1111) and an upper substrate portion (1112). FIG. 12 shows a flow chart of an exemplary embodiment of a method for forming a substrate as described herein. It will be understood that the elements in the drawings are depicted for simplicity and clarity and are not necessarily drawn to scale. For example, the size of some elements in the drawings may be exaggerated relative to other elements to help enhance understanding of the embodiments depicted in the present disclosure.

100:Methods

102,104,106,108,110: Steps

Claims (15)

A method for forming a structure including a photoresist bottom layer, the method comprising the following steps: providing a substrate; forming a photoresist bottom layer overlying a surface of the substrate using a cyclic deposition process; wherein the photoresist bottom layer comprises one or more of an oxide, a nitride, and an oxynitride of a metal; wherein the metal comprises one or more transition metals; wherein forming the photoresist bottom layer comprises forming a lower bottom layer portion and an upper bottom layer portion; and wherein the lower bottom layer portion has a layered structure comprising alternating silicon-containing layered structures and metal-containing layered structures, wherein forming The lower bottom layer portion includes performing a plurality of sub-cycles x and sub-cycles y, wherein the sub-cycles x and the sub-cycles y are performed alternately, wherein the sub-cycle x includes exposing the substrate to a silicon precursor in a reaction chamber; flushing excess of the silicon precursor from the reaction chamber; subjecting the substrate to plasma; and flushing excess reactive species from the reaction chamber; and wherein the sub-cycle y includes exposing the substrate to a metal precursor; flushing excess of the metal precursor from the reaction chamber; exposing the substrate to plasma; and flushing excess of the reactive species from the reaction chamber. The method as described in claim 1, wherein the photoresist bottom layer comprises the metal, oxygen, and carbon, and wherein the metal precursor is an alkoxide or alkamide metal precursor. The method of claim 2, wherein the metal precursor has a general formula M[R(C _x H _y ) _n ] ₄ , wherein M is selected from Ti, Ta, Hf, Zn, and Zr, wherein R is selected from OCH and N, wherein x is 1 or 2, wherein y is 3 to 6, and wherein n is 2 or 3. The method as described in claim 3, wherein M is Ti. The method as described in claim 4, wherein the metal precursor is titanium (IV) isopropoxide. The method as described in claim 3, wherein a carbon precursor is further provided to the reaction chamber during the step of forming the photoresist bottom layer, wherein the carbon precursor comprises one or more of a carboxylic anhydride, toluene, diethylene glycol, triethylene glycol, acetaldehyde, and an organic silicon compound. The method of claim 3, wherein the photoresist bottom layer is formed using a reactant selected from H ₂ O, O ₃ , and H ₂ O ₂ . A method as described in claim 1, wherein the photoresist bottom layer is formed using a plasma ALD or plasma enhanced pulsed CVD method using a plasma, and the plasma is selected from the list consisting of: _H2 plasma, Ar plasma, _O2 plasma, plasma containing _H2 and He, and plasma containing _H2 and Ar. The method as described in claim 3 further comprises a surface treatment step. The method as described in claim 9, wherein the surface treatment step comprises exposing the photoresist bottom layer to one or more carbon-containing compounds, wherein the one or more carbon-containing compounds are selected from the group consisting of: carboxylic anhydride, toluene, diethylene glycol, triethylene glycol, acetaldehyde, and organic silicon compounds. The method as described in claim 3 further comprises a step of forming a carbon-containing layer overlying the photoresist bottom layer, wherein the carbon-containing layer comprises silicon, oxygen, and carbon. The method as described in claim 3 further comprises a step of forming a self-assembly layer overlying the photoresist bottom layer, wherein the self-assembly layer is formed of a material selected from the group consisting of: (n,n-dimethylamino)trimethylsilane, hexamethyldisilazane, (3-bromopropyl)trimethoxysilane, (3-iodopropyl)trimethoxysilane, 3-(trimethoxysilyl)propyl acrylate, trimethoxyphenyl silane, silane), trimethoxy(3,3,3-trifluoropropyl)silane, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, trichloro(phenyl)silane, and trimethoxy(1H,1H,2H,2H-heptadecafluorodecyl)silane. The method of claim 1, wherein the lower bottom layer portion is formed using a metal halide precursor, or wherein the lower bottom layer portion is formed using a metal-containing precursor having a general formula M[R( _CxHy ) _n ] ₄ , wherein M is selected from Ti, Ta, Hf, Zn, and Zr, wherein R is selected from OCH and N, wherein x is 1 to 2, wherein y is 3 to 6, and _wherein n is 2 to 3; and wherein the upper bottom layer portion is formed using a metal-containing precursor having a general formula M[ _R ( _CxHy ) _n ] ₄ , wherein M is selected from Ti, Ta, Hf, Zn, and Zr, wherein R is selected from OCH and N, wherein x is 1 to 2, wherein y is 3 to 6, and wherein n is 2 to 3. The method as claimed in claim 13, wherein the upper bottom layer portion is formed using plasma enhanced ALD or plasma enhanced chemical vapor deposition using a rare gas as a plasma gas. The method as described in claim 3 further comprises a step of exposing the photoresist bottom layer to a surface treatment, wherein the surface treatment comprises a step of exposing the photoresist bottom layer to an organic silicon compound, wherein the organic silicon compound is selected from the list consisting of bis(tripropylsilyl)amine, bis(triethylsilyl)amine, bis(trimethylsilyl)amine, (n,n-dimethylamino)trimethylsilane, (diethylamino)trimethylsilane, (diethylamino)triethylsilane, and (dimethylamino)triethylsilane.